Tag: reptiles

This irascible-looking little guy was recently discovered by biologists on the small island of Nosy Hara, in northern Madagascar. Members of this newly discovered species are on average an inch long from snout to tail tip, a remarkably tiny size that puts them among the world’s smallest reptiles. When not turning their baleful glares at the camera, they run around in a landscape of limestone boulders and leaf fragments and at night roost in low-hanging vegetation no more than a couple inches from the ground. Their diminutive size seems to be the evolutionary result of a phenomenon called island dwarfism, by which animals slowly shrink in size, perhaps in response to the limited resources available on an island (though it also goes the other way, a phenomenon called island gigantism, possibly a result of having few predators).

Ask a group of snake researchers whether our modern snakes evolved from land-loving or ocean-loving lizards, and you’re likely to start a heated argument. But the days of snake-origin squabbles may be coming to a close–researchers have created the first 3-D images of snake fossils and have discovered that their legs are more akin to the legs of land-dwelling lizards than they are to the ocean-dwelling kind.

The researchers studied a 95-million-year-old fossilized snake called Eupodophis descouensi that was found in present-day Lebanon. Published in the Journal of Vertebrate Paleontology, the scientists used a novel 3-D imaging technique called synchrotron-radiation computed laminography:

“Synchrotrons are enormous machines and allow us to see microscopic details in fossils invisible to any other techniques without damage to these invaluable specimens,” said co-author Paul Tafforeau from the European Synchrotron Radiation Facility. [Discovery News]

This fossil of an ancient winged reptile, bought from a farmer in China’s Liaoning province, tells a dramatic tale. About 160 million years ago, a female pterosaur fractured its wing and sank to the bottom of a muddy lake. Somehow, in the process of either dying or decomposing, she expelled a single egg, which has been preserved through the ages.

That’s the story that researchers told in a study published in the journal Science, anyway. And if the remarkably preserved fossil of the reptile Darwinopterus is female, they say, it sheds light on the sex differences and mating rituals of the extinct species. The preserved egg also seems to reveal new details of pterosaur reproduction.

Pterosaurs were the first vertebrates to take to the air, first appearing in the fossil record some 220 million years ago in the late Triassic period. Before their demise 65 million years ago the group evolved to include the largest flying animals ever to live – some had a wingspan of 10 metres. [New Scientist]

They may not be as adorable as sugar gliders, but they’re just as accomplished: Five species of Asian snake have also developed the ability to “fly” or glide from tree to tree, flattening out their bodies to travel up to 80 feet.

Researcher Jake Socha and his team studied the glide of Chrysopelea paradisi snake and took videos of the snakes in flight, which Socha presented at an ongoing meeting of the American Physical Society. He found that before a snake takes the leap it curls its body into a J-shape, and then launches itself from the tree branch. In the air, it flattens its body and undulates, as if slithering through the air.

A tiny fraction of vertebrate species have ever been seen reproducing through parthenogenesis, the fatherless birth of offspring in which the embryo develops without fertilization by a male. Now you can add boa constrictors to that short list: A study in Biology Letters documents the case of a boa that gave birth to 22 offspring over the last two years, all of whom are female and born this unusual way.

“Only with the development and application of molecular tools have we truly begun to understand how common this form of reproduction may be,” lead author Warren Booth [says]. Booth, a research associate at North Carolina State University’s Department of Entomology, and his team first suspected something was up when the mother boa constrictor gave birth, twice, to a total of 22 caramel-colored females. The males housed with the female did not carry the gene for this recessive color trait. [Discovery News]

When Booth’s team analyzed the DNA of the young snakes, they found no evidence of paternity by any of the males who’d mated with their mother previously. Furthermore, the chromosomes of the 22 young gave them away.

While the temperature effects of climate change are expected to be less dramatic in the equatorial regions, the cold-blooded tropical animals that live there may be in for a dramatic shock.

A study published this week in Nature focused on these cold-blooded animals–including insects, amphibians, and lizards–whose body temperatures are not constant, but instead rise and fall with the temperature of their environment. The researchers found that these creatures show great increases in their metabolism from slight changes in temperature; the metabolic increases were on the order of twice that of warm-blooded animals.

“The assumption has been that effects on organisms will be biggest in the place where the temperature has changed the most,” [first author Michael] Dillon said. “The underlying assumption is that … no matter where you start, a change means the same thing. But with physiology, that’s rarely the case.” [Scientific American].

This means that though climate change will be more extreme in toward the Earth’s poles, the cold-blooded animals that live near the equator (where changes should be milder) may react more strongly to the changes.

During the Pleistocene epoch animals thought big: It was the age of the megafauna, when creatures like the mammoth, an 8-foot-long beaver, and a hippopotamus-sized wombat walked the Earth. But these giants vanished one by one, and scientists have long wondered why.

Debate over what caused the megafauna to die out has raged for 150 years, since Darwin first spotted the remains of giant ground sloths in Chile. Possible causes have ranged from human influence to climate change in the past, even to a cataclysmic meteor strike. [BBC]

Now, a discovery on the South Pacific island nation of Vanuatu seems to have answered the question for at least one species. Researchers have turned up the bones of a giant land turtle in a dump used by the people who settled on the islands 3,000 years ago, and lead researcher Trevor Worthy says the evidence strongly suggests that the turtles were hunted into extinction.

80beats aims to bring you all the science news that’s fit to turn into bytes of digital information, but sometimes DISCOVER’s other bloggers get to the juicy news stories first. To make sure you don’t miss anything, here are a couple of links:

Supersenses! Ed Yong at Not Exactly Rocket Science covers two journal articles in which scientists investigated the amazing sense of touch in seal whiskers and sharks’ equally astounding sense of smell in the water. To test the sensitivity of seal whiskers, researchers blindfolded a seal and had him “read” the turbulence of a wake.

For the first time, scientists get to watch as an exoplanet orbits its star—63 light years away. Check out Phil Plait’s Bad Astronomy post for the must-see image. Elsewhere on the Web, National Geographic notes that this planet, Beta Pictoris b, is just a baby. According to the paper published in Science, Beta Pictoris appears to be only a few million years old, yet it’s fully formed–which surprised astronomers who thought that planets take much longer to come into their own.

Finally, a look back to the marine reptiles that ruled the prehistoric seas. A new study suggests that unlike most reptiles, these mighty sea monsters may have been able to regulate their body temperatures, reports Ed Yong. That ability could have allowed these top-of-the-food-chain hunters to swim fast and dive deep, regardless of ocean temperatures.

Herpetologist Chris Reading and his team have been counting snakes through their own surveys and looking at population data going back to 1987 to see what’s happening to snake populations. The alarming findings, to be published soon in Biology Letters, indicate that most of the species studied saw a great decrease in population, with the greatest loss between 1998 and 2002.

Reading’s team monitored 17 different species in different climates—including snakes from Europe, Africa, and Australia—to try to get a global picture. Eleven of the 17 declined sharply over the study’s two-decade-plus period, with some declining as much as 90 percent. Five remained more or less stable. Only one saw a population increase, and a very slight one at that.

“All the declines occurred during the same relatively short period of time and over a wide geographical area that included temperate, Mediterranean and tropical climates,” write the authors. “We suggest that, for these reasons alone, there is likely to be a common cause at the root of the declines and that this indicates a more widespread phenomenon” [Guardian].

Crocodiles like to lurk in the shallows, preparing to pounce. They are not, as a general rule, strong enough swimmers to go on extended ocean cruises whenever they feel like it. Despite this, these creatures managed to reach islands across the South Pacific. How?

Surfing.

A group of scientists led by Craig Franklin, and including the late “Crocodile Hunter” Steve Irwin, studied saltwater crocs from the Kennedy River area of Northeastern Australia for about a year for a study forthcoming in the Journal of Animal Ecology. The team tagged 20 animals with receivers to give both their position and body temperature.

They found that eight crocodiles undertook a total of 42 long-distance journeys of more than 10 kilometres [6.2 miles] per day. In 96% of these trips, the reptiles traveled with the current flow. In contrast, the crocodiles were equally likely to travel with and against the current flow when making short journeys [Nature].

The body temperature reading gave the scientists another way to verify this, besides matching croc travel habits to changing ocean currents. When the tide went against the crocs, they just hung out on the beach and their body temperature rose to 90 degrees F as they soaked up the sun. However, when the current became favorable and they went traveling, their temperatures descended to more like 77 degrees.